my $coderef = \&some_sub;  # $coderef contains a reference to &some_sub
my $results = $coderef->();

##</code><code>##

my $subname = 'some_sub';
my $results = eval "$subname()";
die $@ if $@;

##</code><code>##

my $results = do { no strict 'refs'; $subname->() };

##</code><code>##

use strict;
use warnings;

sub some_sub {
  print "Hello world!\n";
  return 42;
}

my $coderef = \&some_sub;
my $subname = 'some_sub';

print $coderef->(), "\n";
print eval "$subname()", "\n";
die $@ if $@;
print do { no strict 'refs'; $subname->() }, "\n";

__END__
Hello world!
42
Hello world!
42
Hello world!
42